Endothelial Autophagy Dysregulation in Diabetes

Hydrogen sulfide ameliorated endothelial dysfunction in hyperhomocysteinemia rats: Mechanism of IRE1α/JNK pathway-mediated autophagy

Previous studies showed that hyperhomocysteinemia (HHcy) induced endothelial dysfunction by endoplasmic reticulum (ER) stress induction and autophagy stimulation. This study aimed to determine the effect of hydrogen sulfide (H2S) in homocysteine (Hcy)-induced endothelial dysfunction and observe the possible mechanism involved. Male Wistar rats (160-180g) were used and randomly divided into four groups: Control group, HHcy group, HHcy+Sodium hydrosulfide (NaHS) group and NaHS group. Rats were fed with 2% high methionine diet for 8 weeks to set up HHcy model. Plasma concentration of Hcy was measured by ELISA. Endothelium-dependent and non-endothelium-dependent vasodilation of rat renal arteries were determined by myograph. The protein expression of cystathionine-γ-lyase (CSE), ER stress- and autophagy-related proteins in renal arteries or human umbilical vein endothelial cells (HUVECs) were analyzed by western blotting. The endothelial function was impaired in HHcy rats and HUVECs. NaHS supplementation could improve the ACh-induced vasodilation, however it was eliminated by ER stress inducer Tunicamycin (TM) or autophagy inducer Rapamycin. Western blotting in renal arteries showed that Glucose-regulated protein 78 (GRP78) and three branches of ER stress (p-IRE1α, p-PERK, ATF6) , p-JNK1+p-JNK2 were downregulated, simultaneously the autophagy marker Beclin1, LC3BII/LC3BI ratio were decreased and p62 was increased with NaHS treatment in HHcy rats. In HUVECs, IRE1α-JNK induced autophagy was involved in HHcy-induced endothelial dysfunction, while NaHS stimulation reversed the protein expression in IRE1α/JNK-autophagy pathway with Hcy incubation. This study might suggest that endothelial dysfunction induced by HHcy might be correlated with IRE1α-JNK-autophagy axis pathway, which was suppressed by exogenous supplementation of H2S donor, NaHS.

The Role of Autophagy in Vascular Endothelial Cell Health and Physiology

Autophagy is a highly conserved cellular recycling process which enables eukaryotes to maintain both cellular and overall homeostasis through the catabolic breakdown of intracellular components or the selective degradation of damaged organelles. In recent years, the importance of autophagy in vascular endothelial cells (ECs) has been increasingly recognized, and numerous studies have linked the dysregulation of autophagy to the development of endothelial dysfunction and vascular disease. Here, we provide an overview of the molecular mechanisms underlying autophagy in ECs and our current understanding of the roles of autophagy in vascular biology and review the implications of dysregulated autophagy for vascular disease. Finally, we summarize the current state of the research on compounds to modulate autophagy in ECs and identify challenges for their translation into clinical use.

Promoting collateral formation in type 2 diabetes mellitus using ultra-small nanodots with autophagy activation and ROS scavenging

BACKGROUND

Impaired collateral formation is a major factor contributing to poor prognosis in type 2 diabetes mellitus (T2DM) patients with atherosclerotic cardiovascular disease. However, the current pharmacological treatments for improving collateral formation remain unsatisfactory. The induction of endothelial autophagy and the elimination of reactive oxygen species (ROS) represent potential therapeutic targets for enhancing endothelial angiogenesis and facilitating collateral formation. This study investigates the potential of molybdenum disulfide nanodots (MoS2 NDs) for enhancing collateral formation and improving prognosis.

RESULTS

Our study shows that MoS2 NDs significantly enhance collateral formation in ischemic tissues of diabetic mice, improving effective blood resupply. Additionally, MoS2 NDs boost the proliferation, migration, and tube formation of endothelial cells under high glucose/hypoxia conditions in vitro. Mechanistically, the beneficial effects of MoS2 NDs on collateral formation not only depend on their known scavenging properties of ROS (H2O2, •O2-, and •OH) but also primarily involve a molecular pathway, cAMP/PKA-NR4A2, which promotes autophagy and contributes to mitigating damage in diabetic endothelial cells.

CONCLUSIONS

Overall, this study investigated the specific mechanism by which MoS2 NDs mediated autophagy activation and highlighted the synergy between autophagy activation and antioxidation, thus suggesting that an economic and biocompatible nano-agent with dual therapeutic functions is highly preferable for promoting collateral formation in a diabetic context, thus, highlighting their therapeutic potential.

The role of autophagy in insulin resistance and glucolipid metabolism and potential use of autophagy modulating natural products in the treatment of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a severe, long-term condition characterised by disruptions in glucolipid and energy metabolism. Autophagy, a fundamental cellular process, serves as a guardian of cellular health by recycling and renewing cellular components. To gain a comprehensive understanding of the vital role that autophagy plays in T2DM, we conducted an extensive search for high-quality publications across databases such as Web of Science, PubMed, Google Scholar, and SciFinder and used keywords like 'autophagy', 'insulin resistance', and 'type 2 diabetes mellitus', both individually and in combinations. A large body of evidence underscores the significance of activating autophagy in alleviating T2DM symptoms. An enhanced autophagic activity, either by activating the adenosine monophosphate-activated protein kinase and sirtuin-1 signalling pathways or inhibiting the mechanistic target of rapamycin complex 1 signalling pathway, can effectively improve insulin resistance and balance glucolipid metabolism in key tissues like the hypothalamus, skeletal muscle, liver, and adipose tissue. Furthermore, autophagy can increase β-cell mass and functionality in the pancreas. This review provides a narrative summary of autophagy regulation with an emphasis on the intricate connection between autophagy and T2DM symptoms. It also discusses the therapeutic potentials of natural products with autophagy activation properties for the treatment of T2DM conditions. Our findings suggest that autophagy activation represents an innovative approach of treating T2DM.

Endothelial Cell Aging and Autophagy Dysregulation

Entropy is a natural process that affects all living cells, including senescence, an irreversible physiological process that impairs cell homeostasis. Age is a significant factor in disease development, and the pathogenesis of endothelial cell aging is multifactorial. Autophagy dysfunction accelerates endothelial cell aging and cell death, while autophagy preserves endothelial cell youthfulness through intracellular homeostasis and gene expression regulation. Sirt, mTORC1, and AMPK are youthfulness genes that induce autophagy by inhibiting mTOR and upregulating FIP200/Atg13/ULK1. Aged endothelial cells have decreased levels of Lamin B1, γH2AX, Ki67, BrdU, PCNA, and SA β-Gal. Maintaining healthy young endothelial cells can prevent most cardiovascular diseases. Autophagy targeting is a potential future therapeutic strategy to modify endothelial cell age and potentially slow or reverse the aging process. This article provides state-of-the-art research on the role of autophagy in endothelial cell aging. Hypothesizing that autophagy dysregulation is associated with early endothelial cell dysfunction and further clinical sequelae, including atherosclerosis formation, leading to various cardiovascular diseases.

Autophagy and diabetes

The current literature findings on autophagy’s beneficial and detrimental roles in diabetes mellitus (DM) and diabetes-related comorbidities were reviewed. The effects of oral hypoglycaemic medicines and autophagy in DM. Autophagy plays an important function in cellular homeostasis by promoting cell survival or initiating cell death in physiological settings was also assessed. Although autophagy protects insulin-target tissues, organelle failure caused by autophagy malfunction influences DM and other metabolic diseases. Endoplasmic reticulum and oxidative stress enhance autophagy levels, making it easier to regulate stress-induced intracellular changes. Evidence suggests that autophagy-caused cell death can occur when autophagy is overstimulated and constitutively activated, which might prevent or develop DM. Even though the precise role of autophagy in DM complications is uncertain, deregulation of the autophagic machinery is strongly linked to beta cell destruction and the aetiology of DM. Thus, improving autophagy dysfunction is a possible therapeutic objective in treating DM and other metabolic disorders.